Me to son;
"This evening you are going to experience the Merovingian Principle"
Son;
"What's that?"
Me;
"I drink too much tea, I have to go to the toilet.
You chew gum in class, you get detention.
You don't go to detention, teacher phones me (which really pi**e* me off at work.) and you don't go climbing this evening.
Voila the Merovingian Principle! Also known as cause and effect."
If looks could kill!